The invention relates generally to cable shields and more particularly to a cable shield closed with an adhesive composition.
It is known to cover cables that carry electrical signals with RF or electromagnetic (hereinafter collectively xe2x80x9cRFxe2x80x9d) shields formed, for example, with conductive fabric or foil overwraps that are closed or sealed by various methods. Some methods employ snap buttons, but this can lack permanence and can be lead to leakage between the snap points. Other closures employ zippers, hook and loop closures and rib-in-groove closures. However, such closures also lack sufficient permanence or durability and can lead to unsatisfactory RF shields.
It is also known to close cable shields with adhesives. Some adhesive are applied in a liquid state and can be inconvenient to use. Others are covered with release strips, but can be difficult to use if the adhesive coated portion unintentionally contacts the wrong location of the cable shield, or some other object such that repositioning can be difficult and closures having a sloppy appearance, loose or too fight a fit or unsatisfactory shielding can result.
Accordingly, it is desirable to provide an improved cable shield and method of closing the cable shield, which overcomes disadvantages of the prior art.
Generally speaking, in accordance with the invention, a cable shield is provided in the form of a sheet having top and bottom surfaces and can include permanent adhesive compositions at edges thereof which can be dry to the touch and which will only bond at the desired location. Adhesives in accordance with preferred embodiments in the invention can also stay unbonded or weakly bonded for sufficiently long periods of time to permit readjustment of the closure, so that the desired fit can be achieved.
The shield can be formed as an elongated sheet with a top/inner surface which will wrap around the cable and a bottom, outer surface, which will face outwards from the cable. The adhesive composition can be disposed as a thin strip at least along one edge of the upper surface of the shield, and as a corresponding complementary thin strip on the lower surface, along the opposite edge, so that when the shield is wrapped around the cable, the strips of the adhesive composition can be contacted to each other. The adhesive is advantageously a pressure sensitive type of adhesive, which can be permanent in nature, which can be formed with a mixture of solid particles in sufficient volume or location that the adhesive will be dry to the touch and substantially only bond to another surface containing the same or similar adhesive. Thus, the solid particles can occupy sufficient area of the surface, so that there is substantially no adhesive bonding when the adhesive contacts most materials. However, when a first coat of adhesive contacts a second surface coated with the adhesive, and pressure is applied, sufficient deformation of the adhesive layers is achieved, such that the pressure sensitive adhesive materials from each coating portion come in contact with each other and the two layers bond together. By using electrically conductive solid particles, such as metallic particles, the adhesive bond itself can be made electrically conductive and improve the RF shielding properties of the closure.
Accordingly, it is an object of the invention to provide an improved cable shield.
Another object of the invention is to provide an improved method of making and closing a cable shield.
The invention accordingly comprises the several steps and the relation of one and more of such steps with respect to each of the others, and the article possessing the features, properties, and the relation of elements, which are exemplified in the following detailed disclosure, and the scope of the intentional will be indicated in the claims.